Gases do not conduct heat well.
Do you see that blank, open space after the word "potential ..." ?
There's supposed to be a number there that actually tells us the value of the potential. Without that number ... and a lot more description of the whole scenario here ... there's no possible answer to the question.
Soil profile includes all the sections/ horizons of the vertical soil depth from top to bottom including the transitions from one horizon to another. A soil horizon is a distinct layer/section of soil with more or less the same texture. Therefore, a soil profile is made of soil horizons.